In recent years a number of high volume electrostatic copy machines have been introduced. In order to take advantage of the high speed copying capabilities of these machines, document handlers adapted to feed the documents to be copied to the platen of the copy machine and remove them therefrom have been utilized to reduce the time required for an operator to place and remove documents. Further, to cope with the large quantities of copies produced, collators of the type illustrated in U.S. Pat. No. 3,830,590, commonly assigned with the instant application, have been introduced for collating the copies to minimize operator involvement with the copying process. Following these developments, the need for a reproduction machine which would reproduce on both sides of a sheet of paper, ordinarily referred to as duplex copying was recognized. This presents a number of problems in a copy reproduction system adapted to produce both single-sided copy and duplex copy in that the machine must be capable of routing single-sided copy sheets directly to the collator, must be adapted for returning single-sided copy sheets to a paper supply tray in preparation for copying on the opposite side of the sheet to produce duplex copies, and must be adapted to invert the duplex copy to provide the proper orientation thereof prior to passage to the collator if the correct page order is to be maintained so that the finished copies are ready for stapling or binding without operator involvement. Sheet inverter-reversors also find utility in document handlers for turning over documents after imaging of the first side for imaging or exposing the reverse side. Further, certain automatic document handlers may require inversion and reversal of a document when operated in an automatic recirculation mode for repetitive imaging of the document. Sheet feed inverting mechanisms of the type illustrated in U.S. Pat. No. 3,523,678 and U.S. application Ser. No. 429,252 now U.S. Pat. No. 3,856,295 commonly assigned with the instant application, may be employed for this purpose. However, most known inverters are capable of handling sheet material within a fairly narrow size range and paper weight.
At the high speeds encountered, an inverter-reverser must be provided that will positively handle light weight paper without damaging the leading or trailing edges of the paper. For heavy weight paper, the device must be capable of coping with the high inertial forces necessary for inverting the sheets at high speed. Further, since a wide variety of paper stock may be encountered, it is desirable to provide a device which is sheet size insensitive, that is, one which will handle a variety of sheet sizes without the necessity for specialized operator adjustment thereto or extensive sensing devices to sense the size of the sheets being fed to the inverter.
It is therefore an object of this invention to provide a mechanism adapted to deliver single-sided copy sheets to the collator, or if duplex copies are required, to route the single-sided copy to a duplexing paper tray and after the duplex copy is produced, route the duplex copy sheet through a self-actuating inverter to the collator to provide the proper sheet orientation in the collator.